Multilayered pressure vessel and method of manufacturing the same

ABSTRACT

A multilayered pressure vessel ( 10 ) fabricated from at least one single ply sheet of flexible material ( 100 ) having an approximate longitudinal midline which divides the material into an inner portion ( 130 ) having an inner surface, an outer surface, an edge, a seam allowance, and a width, and an outer portion having an inner surface, an outer surface, an edge, a seam allowance, and a width. The width of the outer portion ( 120 ) is greater than the width of the inner portion ( 140 ). A primary seam ( 250 ) binds the outer portion and the inner portion to the material sheet at the midline proximate the outer portion edge and inner portion edge. The sheet ( 100 ) is wrapped into a continuous substantially 720 degree wrap to form a generally cylindrical vessel body having possible multiple fluid passageways, at the election of the user. The primary seam ( 250 ) is concealed.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally both to devices for conveying orstoring gasses and to structural elements such as columns, beams,struts, and the like. More particularly, the present invention relatesto a light weight inflatable pneumatic structural members deployed intoserviceable condition by internal gas pressure. Even more particularly,the present inventions relates to a multilayered pressure vesselsuitable for use in storing and conveying gasses, and especiallywell-suited for use as an inflatable load-bearing element. Alsodisclosed is a method of manufacturing the same.

2. Background Art

By definition pressure vessels comprise those vessels that have aninternal pressure higher than the external atmospheric pressure. Suchvessels include those that contain fluids, i.e., fluid storage tanks,and those that convey fluids, such as hoses. It is known to fabricatepressure vessels of flexible rather than rigid material, as this offersa reduction of mass and storage volume compared to rigid materialsystems. However, it is a relatively recent development in thetechnology of structural materials to compose columns, beams, struts,trusses, and the like, of inflatable rather than rigid materials. Thisadvancement is still becoming fully appreciated, and the contemplatedfields of use continue to expand rapidly.

In manufacturing inflatable structural members, the primary structuralrequirements that inform the design and selection of materials include:(1) general compressive buckling; (2) beam stiffness and naturalfrequency; and (3) beam bending buckling. Design parameters include: (1)the radius of the tube; (2) tube thickness; (3) tube length; (4) themodulus of elasticity; and (5) material density. Inflatable structuralmembers have been devised to possess sufficiently desirable structuralcharacteristics to enable use in a variety of fields. Inflatablestructural members are even contemplated for use in extreme and exoticenvironments, most notably outer space.

For instance, as noted by S. L. Veldman and C. A. J. R. Vermeeren inInflatable Structures in Aerospace Engineering—an Overview (April 2001),inflatable circular cylindrical beams are able to support structuressuch as solar array systems, telescope mirrors, sun shields and solarsails, truss structures, and the like. They may also be employed inpermanent and temporary inflatable space habitats, and even in reentryand recovery vehicles. The authors note that in such applications, thelow mass, low storage volume and ease of deployment are factors thatreduce cost considerably.

More conventional applications are well known, and range across adiverse spectrum of possibilities, including columns, beams, booms,trusses, struts, cantilevers, shelters, linear actuators, ladders,antennas, masts, frame links, and so forth. The obvious advantage isthat the potential structure may be transported to the construction sitein a relatively collapsed or flat condition, perhaps on a reel or inracks, and it may then be deployed and installed in a structure. Ifrigidized, it may remain relatively permanent; if not, it may becollapsed for storage and transport once again.

The advantages of flexible structural members were recognized at leastas early as 1968, when U.S. Pat. No. 3,364,623 was issued to theCanadian Peter Isaac. His patent discloses an inflatable structuralmember made of stiff resilient material which is normally flexible andcapable of being stored on a reel, but becomes erectly rigid wheninflated. The member is stored on a reeled state in the flexible stateand may be fed from the reel in a rigid state in a cantilever mannerwithout guidance other than from the reel. The member is capable ofcarrying tensile, compressive, or flexural loads after unreeled.

A later, though not significantly more mature, expression of the art isillustrated in U.S. Pat. No. 4,514,447, issued to Boxmeyer in 1985,which teaches a lightweight, inflatable structural member, having asubstantially tubular shape and sealed at both ends, including an innerlining to maintain internal pressure upon inflation. The inner lining iscovered with a filament reinforced matrix structure comprising resinimpregnated filaments of high tensile strength. The uninflatedstructural member is stowable in a collapsed condition. Curing of theresin matrix is inhibited by storing the collapsed member at a lowtemperature. Prior to use, the member is inflated with a fluid andheated to enable curing of the resin matrix.

This method of manufacturing a rigid structural member by inflatableflexible material and coating or otherwise rigidizing the material withresin was recognized much earlier, in U.S. Pat. No. 3,138,506, to Ross,which discloses a method of manufacturing an article of stiffenedfibrous material comprising the steps of providing a pliable articlehaving spaced fibrous walls and ties connecting the spaced walls;inflating the fibrous article; applying a resin bonded fibrous materialover the inflated article; and hardening the resinous band while thearticle is inflated to tension the material.

The foregoing patents reflect the current state of the art of which thepresent inventor is aware. Reference to, and discussion of, thesepatents is intended to aid in discharging Applicant's acknowledged dutyof candor in disclosing information that may be relevant to theexamination of claims to the present invention in various nationaloffices. However, it is respectfully submitted that none of theabove-indicated patents disclose, teach, suggest, show, or otherwiserender obvious, either singly or when considered in combination, theinvention described and claimed herein.

Additionally, and as will be readily appreciated, the structuralelements taught in each of Boxmeyer and Ross require more than pneumaticpressure to provide the desired structural characteristics, and afterrigidization they are incapable of collapse for storage andtransportability. Furthermore, the structural member of Isaac may befabricated from flexible material, but the manufacturing process entailsuse of a tube to which upper and lower members, joined by hinges, areaffixed. Thus, provision of an article already comprising a pressurevessel, namely a tube, is a predicate to the construction of the deviceshown in Isaac.

Accordingly, it would be desirable to provide a pressure vesselfabricated from flexible material that may be adapted for a variety ofuses ranging from use as structural member when inflated, to use as afluid conveyance means when uninflated and configured as a hose orfilter. It would further be desirable that such a member be capable ofcollapse for easy storage and transport. Finally, it would be desirableto have an inexpensive and mechanically simple means of constructingsuch a pressure vessel.

DISCLOSURE OF INVENTION

The above-indicated needs are met by the present invention, which has anumber of advantages over the prior art.

It is an object of the present invention to provide a new and improvedmultilayered or multi-ply pressure vessel that is readily adapted foruse as a structural member.

It is another object of the present invention to provide a new andimproved multilayered pressure vessel that may be readily adapted foruse as a fluid container and/or fluid conveyor.

A further object or feature of the present invention is to provide a newand improved multilayered pressure vessel suitable for use as a fluidfilter.

An even further object of the present invention is to provide a new andimproved multilayered pressure vessel easily manufactured from a singlesheet of flexible material.

A still further object of the present invention is to provide a new andimproved multilayered pressure vessel easily modified at manufacture tohave discrete compartments for containing, conveying, and/or segregatingvarious materials.

Yet another object of the present invention is to provide a new andimproved multilayered pressure vessel having a single internal seamwhich distributes tensile forces throughout the interior of the vessel.

A further object of the present invention is to provide a multilayered,multi-chambered, and multipurpose pressure vessel for selectivelyconveying and discharging one or more fluids.

Yet another object of the present invention is to provide multilayeredpressure vessel having at least two interior passages for simultaneouslyconducting two different fluids in two different states, namely, gas andliquid.

Another object of the present invention is to provide a method ofmanufacturing a multilayered pressure vessel that is simple in conceptand in execution and that obviates the need for expensive machinery.

Other novel features which are characteristic of the invention, as toorganization and method of operation, together with further objects andadvantages thereof will be better understood from the followingdescription considered in connection with the accompanying drawing, inwhich preferred embodiments of the invention are illustrated by way ofexample. It is to be expressly understood, however, that the drawing isfor illustration and description only and is not intended as adefinition of the limits of the invention. The various features ofnovelty which characterize the invention are pointed out withparticularity in the claims annexed to and forming part of thisdisclosure. The invention resides not in any one of these features takenalone, but rather in the particular combination of all of its structuresfor the functions specified.

The present invention is a multilayered pressure vessel which is readilyadapted for use as a volumetric container, a hose, a filter, and astructural member, such as a beam, boom, truss, strut, column, and thelike. In a first preferred embodiment, the apparatus may be summarilycharacterized as a multilayered pressure vessel having at least onesingle ply sheet of flexible material having an approximate longitudinalmidline dividing the sheet into an unequal geometry of inner and outerportions. Each portion has an inner surface, an outer surface, an edge,a seam allowance, and a width. The width of the outer portion is greaterthan the width of the inner portion. In an early manufacturing step, theouter and inner portions are folded to created side-by-side passagewaysin a substantially figure-8 multi-ply configuration. A seam is placedthrough the outer and inner portions and the sheet of flexible materialat the approximate longitudinal midline and near the outer and innerportion edges. The inner portion is then pulled into and down the outerportion passageway while the outer portion is turned inside out and overthe inner portion, so that at the completion of this manufacturing stepa substantially continuous 720 degree wrap of material forms a generallycylindrical vessel body in which the outer surface of the outer portionforms the outside surface of the pressure vessel body, the inner surfaceof the inner portion forms the innermost surface of the pressure vesselbody, the outer surface of the inner portion and the inner surface ofthe outer portion are in face-to-face relation, and the seam isconcealed by the seam allowance of the outer portion.

The vessel body formed according to the inventive method summarizedabove may be equipped with end fittings for introducing and containingfluids in the vessel body and for connecting separate pressure vesselsto one another or to other structures. Additionally, the manufacturingmethod facilitates the attachment of exterior and interior surfacereinforcement sleeves, handles, exterior surface textures, and the like.It also facilitates the inclusion of a plurality of interiorpassageways. It does so because the material is ultimately turnedinside-out in manufacture. Thus, in the manufacturing process, thesurface that will ultimately be an interior surface in the vessel bodyis exposed as an exterior surface in the first steps of manufacture.Thus, until the final stages of manufacturing, there is provided aworking surface for easy modification of the interior surface accordingto the anticipated end uses.

There has thus been broadly outlined the more important features of theinvention in order that the detailed description thereof that followsmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are, of course, additionalfeatures of the invention that will be described hereinafter and whichwill form additional subject matter of the claims appended hereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based readily may be utilized as a basis for the designingof other structures, methods and systems for carrying out the severalpurposes of the present invention. It is important, therefore, that theclaims be regarded as including such equivalent constructions insofar asthey do not depart from the spirit and scope of the present invention.

Further, the purpose of the Abstract is to enable the national patentoffice(s) and the public generally, and especially the scientists,engineers and practitioners in the art who are not familiar with patentor legal terms or phraseology, to determine quickly from a cursoryinspection the nature and essence of the technical disclosure of theapplication. The Abstract is neither intended to define the invention ofthis application, which is measured by the claims, nor is it intended tobe limiting as to the scope of the invention in any way.

Certain terminology and derivations thereof may be used in the followingdescription for convenience in reference only, and will not be limiting.For example, words such as “upward,” “downward,” “left,” and “right”would refer to directions in the drawings to which reference is madeunless otherwise stated. Similarly, words such as “inward” and “outward”would refer to directions toward and away from, respectively, thegeometric center of a device or area and designated parts thereof.References in the singular tense include the plural, and vice versa,unless otherwise noted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an end view in elevation of a single sheet of flexible fabric(viewed on edge), showing the geometry and general relative dimensionsof the various portions of the inventive multilayered pressure vesselbefore construction;

FIG. 2 is an end view in elevation of the fabric sheet of FIG. 1 shownwith the outer and inner passageways of the inventive vessel formed withfolds and also showing placement of the single primary seam of theconstructed vessel;

FIG. 3 is an end view in elevation of the constructed multilayeredpressure vessel of the present invention in its most elemental form;

FIG. 4 is a perspective view showing an intermediate manufacturing stepand illustrating means for the final step for forming the vessel body;

FIG. 5 is an end view in elevation showing the configuration of thefirst preferred embodiment after construction, and particularlyillustrating how the vessel material forms a continuous 720 degree wrapto comprise the essential or bare vessel body;

FIG. 6 is an end view in elevation of preconstruction fabric sheetemployed in a second preferred embodiment of the inventive multilayeredpressure vessel, showing the inner and outer portions, the midpoint ofthe fabric, the prospective seam allowances, and the location ofpossible attachment members,

FIG. 7 is an end view in elevation of the fabric sheet of FIG. 6 shownwith the outer and inner passageways of the inventive vessel formed withfolds and also showing placement of the single primary seam of theconstructed vessel;

FIG. 8 is an end view of the second preferred embodiment of theconstructed multilayered pressure vessel of the present invention,highlighting placement of attachment members on the interior andexterior surfaces of the vessel;

FIG. 9 is a partial cross-sectional side view in elevation of certainfitting elements adapted for installation on an end of the pressurevessel body;

FIG. 9A is a partial cross-sectional perspective view of the completefitting of FIG. 9, also showing the terminal fitting elements;

FIG. 10 is a perspective view of an end of a third preferred embodimentof the inventive pressure vessel, showing the constructed vessel havinga plurality of sleeves for the insertion of tuning cables;

FIG. 11 is a perspective view of the end of a tuning cable;

FIG. 12 is a perspective view of the pressure vessel end of FIG. 10having an end fitting fully installed;

FIG. 13 is a side perspective view of a complete pressure vessel withend fittings at each end of the pressure vessel and tuning cablesinstalled in sleeves disposed between the ends;

FIG. 14 is an end view in elevation of a pressure vessel body showing analternative arrangement of tuning cable sleeves and tuning cables,disposed between layers in the interior of the multilayered pressurevessel;

FIG. 15 a cross-sectional end view in elevation of airfoil or winghaving tubular pressure vessels forming a plurality of wing spars;

FIG. 16 is perspective view showing a bundle of tubular pressure vesselsforming a pressure tank having multiple inflatable chambers;

FIG. 17 is a perspective view of a tubular pressure vessel having anexteriorly attached flange having grommets;

FIG. 18 is a side view in elevation showing the pressure vessel of FIG.17 draped from I-hooks;

FIG. 19 is an end view in elevation showing connection means for abundle of tubular pressure vessels;

FIG. 20 is an end view showing alternative connection means forside-by-side tubular vessels;

FIG. 21 is an end view showing an alternative embodiment of theinventive pressure vessel having four layers of material forming thepressure vessel body;

FIG. 22 is an end view in elevation showing an embodiment of theinventive pressure vessel having multiple interior fluid passages;

FIG. 23 is a top plan view of a section of fabric sized for constructioninto a cone-shaped pressure vessel; and

FIG. 24 is a cone-shaped pressure vessel constructed of the fabricsection of FIG. 23.

REFERENCE NUMBER LEGEND

Embodiments of the invention are shown in FIGS. 1–24. The elements inFIGS. 1–24 are as follows:

-   10 vessel body of the first preferred embodiment of the multilayered    pressure-   100 flexible fabric sheet-   110 outer portion-   120 width of outer portion-   130 inner portion-   140 width of inner portion-   150 outer surface of outer portion-   150 a exterior surface of (fully formed) multilayered pressure    vessel-   160 inner surface of outer portion-   165 outer portion edge-   170 outer portion seam allowance-   180 outer surface of inner portion-   190 inner surface of inner portion-   195 inner portion edge-   200 inner portion seam allowance-   210 outer portion fold-   210 a direction of fold for outer portion-   220 inner portion fold-   220 a direction of fold for inner portion-   230 outer passageway-   240 inner passageway-   250 primary seam-   250 a–d hidden seam segments-   M approximate longitudinal midline of fabric sheet-   260 intermediate portion fabric sheet-   270 upper flap inner portion-   280 lower flap of outer portion-   290 thread-   300 sewing machine-   310 inner portion pulling means-   320 inner portion fold-   330 line affixed to inner portion fold-   340 proximate end of fabric-   350 distal end of fabric-   360 potential space separating outer portion inner surface and inner    portion outer surface-   400 flexible fabric sheet for second preferred embodiment-   410 outer portion-   420 inner portion-   430 width of outer portion-   440 width of inner portion-   450 attachment element-   460 attachment element-   470 attachment means-   480 attachment means-   490 outer surface of outer portion-   500 inner surface of inner portion-   510 vessel body of second preferred embodiment-   520 seam-   520 a–d hidden segments 510 a–d of seams-   600 end fitting (selected elements)-   610 cylindrical pressure vessel body-   620 retaining ring-   630 cap neck-   640 threaded portion of cap neck-   650 retaining washer-   660 pressure lock ring-   670 threaded portion of pressure lock ring-   680 inflatable bladder-   690 valve stem-   700 port plug-   710 washer-   720 nut-   730 oval-shaped opening in terminal side of cap neck-   740 terminal side of cap neck-   750 interior flange of port plug-   800 third preferred embodiment of inventive pressure vessel-   810 a–d tuning cable passages-   820 exterior surface of outer portion-   840 a–d fabric strips affixed to outer portion to form tuning cable    sleeves-   850 a–d edges of fabric strips-   860 tuning cable (generally)-   860 a–d tuning cables-   870 threaded pin-   880 nut-   900 alternative end fitting (generally)-   900 a first end fitting-   900 b second end fitting-   910 tunable length of vessel body-   920 cap neck-   930 pressure lock ring-   940 rim of pressure lock ring-   950 oval shaped opening on terminal side of cap neck-   960 port plug-   970 hole for valve stem-   980 valve stem-   990 threaded studs-   1000 fourth preferred embodiment of inventive pressure vessel-   1010 vessel body of fourth preferred embodiment-   1020 tuning cable sleeves-   1030 interior surface of outer portion of vessel body-   1040 outer portion of vessel body-   1050 tuning cables-   1100 airfoil having tubular pressure vessel spars-   1120 upper airfoil surface-   1130 lower airfoil surface-   1200 multi-chambered tubular pressure vessel structural member-   1210 tubular pressure vessels-   1220 end fittings-   1230 fluid conduits-   1240 gas inlet-   1300 fifth preferred embodiment of inventive pressure vessel-   1310 vessel body of fifth preferred embodiment-   1320 flange-   1330 seams attaching flange to outer surface of vessel body-   1340 outer surface of vessel body-   1350 grommets-   1360 support line-   1400 connection means for connecting plurality of pressure vessels-   1410 outer surfaces of vessel bodies-   1500 connection means-   1510 outer surfaces of vessel bodies-   1600 sixth preferred embodiment of inventive pressure vessel-   1610 first fabric sheet-   1620 second fabric sheet-   1630 first fluid passageway-   1640 second fluid passageway-   1650 third fluid passageway-   1660 fourth fluid passageway-   1670 a–d first through fourth layers of vessel body-   1680 primary seam-   1700 seventh preferred embodiment of inventive pressure vessel-   1710 vessel body of seventh preferred embodiment-   1720 first interior fluid passage-   1730 second interior fluid passage-   1740 third interior fluid passage-   1750 first material attachment-   1750 a first edge of first material attachment-   1750 b second edge of first material attachment-   1760 second material attachment-   1760 a first edge of second material attachment-   1760 b second edge of second material attachment-   1770 third material attachment-   1770 a first edge of third material attachment-   1770 b second edge of third material attachment-   1780 interior surface of the vessel body-   1800 fabric sheet for eighth preferred embodiment of inventive    pressure vessel-   1810 outer portion of fabric sheet for eighth preferred embodiment-   1820 inner portion-   1830 midline axis (of symmetry)-   1840 first side (of outer portion)-   1850 second side (of outer portion)-   1860 third side (of outer portion)-   1870 first side (of inner portion)-   1880 second side (of inner portion)-   1890 third side (of inner portion)-   1900 vessel body of eighth preferred embodiment-   1910 large opening-   1920 small opening-   1930 passageway between inner and outer portions

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIGS. 1 through 24, wherein like reference numerals referto like components in the various views, FIGS. 1 and 1 a are,respectively, an end view in elevation and a top plan view of a singlesheet of flexible fabric 100, showing the geometry and relative generaldimensions of the various portions of the inventive vessel beforeconstruction. The sheet may be a single ply sheet or it may bemulti-ply. In either case, in the first preferred embodiment of thepresent invention, the fabric sheet it is preferably substantiallyrectangular and elongate and is unevenly divided by an approximatelongitudinal midline M into an outer portion 110 having a width l 120,and an inner portion 130 having a width l₁ 140, which is smaller thanthat if the outer portion. The inner and outer portions, each comprise aquadrilateral, defined by sides 110 a, 110 b, 110 c and M, and 130 a,130 b, 130 c and M, respectively. In the first preferred embodiment ofthe inventive apparatus, the quadrilaterals comprising the inner andouter portions are substantially rectangular. The disparate widths ofthe inner and outer portions are necessary to achieve the configurationof the finished inventive article.

The outer portion of the fabric sheet has an outer surface 150, an innersurface 160, an outer portion edge 165, and a seam allowance 170. Theinner portion has an outer surface 180, and inner surface 190, an innerportion edge 195, and a seam allowance 200. This view also illustratesthe direction of fold 210 a, 220 a, for the outer and inner portions,respectively.

FIG. 2 shows the fabric sheet of FIG. 1 with the outer passageway 230and inner passageway formed from making an outer portion fold 210 and aninner portion fold 220. The outer portion is folded under the fabricsheet such that its edge extends slightly beyond the approximate midlineto form its seam allowance. The inner portion is folded over the fabricsheet such that its edge extends slightly beyond the approximate midlineto form its seam allowance. A single primary seam 250 is placed throughall layers of the fabric, including the seam allowances, atsubstantially the approximate midline M. Placement of the primary seamis made before the final construction steps and creates the dualcontinuous loop shown in this figure. The final construction stepscomprise pulling inner portion 130 into outer passageway 230 and pullingit lengthwise down the outer passageway from the proximal end 340 of thefabric while simultaneously turning outer portion 110 inside out andover the inner portion beginning from the distal end 350 and proceedingtowards the proximal end (see also FIG. 4).

FIG. 3 is an end view in elevation of the first preferred embodiment ofa fully constructed multilayered pressure vessel 10 in its mostelemental form having a simple tubular or cylindrical body. This viewshows that the outer portion 110 and inner portion 130 may be spacedapart to define an outer passageway 230. Alternatively, the outer andinner portions may be sized so that there is no effective spaceseparating the portions when fully assembled. Whether spaced apart orfully approximated, the inner surface of the outer portion and the outersurface of the inner portion oppose one another in a face-to-facerelation. Details of this configuration are shown in FIG. 5.

FIG. 4 is a perspective view illustrating the condition of the pressurevessel during manufacture, showing an intermediate manufacturing stepand illustrating means for the final step for forming the vessel body.In this view it is shown that the pressure vessel of the presentinvention is manufactured in a simple manner, entailing the steps of:(a) providing a generally elongate fabric sheet 100 having a proximalend 340, a distal end 350, and first and second edges 165, 195; (b)folding the sheet by bringing the first edge downward and under thesheet to form an outer portion 110 having an outer portion flap 280, anouter passageway 230, and a first seam allowance 170; (c) folding thesheet again by bringing the second edge upward and over the sheet toform an inner portion 130 having an inner portion flap 270, an innerpassageway 240, and a second seam allowance 200, and such that the firstand second seam allowances overlap and a section of fabric sheet isinterposed between the inner and outer portion flaps and the first andsecond seam allowances to form a multilayered configuration 20; (d)sewing a seam to make a single primary seam 250, which binds the layersof the multilayer configuration together; (e) providing pulling means310 and affixing the pulling means to the inner portion upper flap 270at the proximate end 340 of the fabric and preferably at the fold 320 ofthe inner portion (in very small and lightweight embodiments, thepulling means may comprise nothing more than gripping the fold with thehuman hand; however, under most circumstances it would be preferable tohave a line 330 or functionally comparable pulling means anchored to andextended from the inner portion fold 320, into and through outerpassageway 230, to facilitate the process of pulling inner portion 130into the outer passageway); (f) pulling the inner portion into outerpassageway 230 at the proximate end 340 while simultaneously turningouter portion 110 inside out by pulling its distal end 350 over theincreasingly overlapping outer and inner passageways, which effectivelyturns the entire apparatus inside out and pulls primary seam 250 inside,interposing it between the outer portion 110 and the inner portion 130,and thereby hiding seam segments 250 a, 250 b, 250 c, and 250 d.

By constructing the vessel body in this fashion, the seam is concealedand not exposed to outside forces that cause wear and tear of the seamor otherwise expose it to degradation. Depending on the materialsemployed and the scale of production, this simple manufacturing processcan eliminate the need for elaborate machinery, though it iscontemplated that many industrial applications will call for a vesselbody of sufficient size and strength to necessitate mechanical forces toeffect steps (e) and (f), above.

As shown in FIG. 5, when fully configured, the folding and manipulationof the fabric inverts the position of outer portion inner surface 160and inner portion outer surface 180 so that they are facing one anotherand, depending on portion dimensions, such that they may be fullyapproximated and in continuous physical contact along their width(except for interruptions at the seam allowances). The outer surface 150of the outer portion 110 becomes the exterior surface 150 a of thevessel body 10, and the inner surface 190 of the inner portion 130becomes the innermost interior surface 190 a of the vessel body. If itis desired that the inner and outer portions be in complete andcontinuous contact (for instance, when the pressure vessel functions asa volumetric container or a high pressure hose), the inner portion outersurface and the outer portion inner surface may be coated with anadhesive before folding to provide a strong binding between the layers.This will enhance the pressure resistance of the pressure vessel.

FIG. 5 also shows how the configuration of the first preferredembodiment of the inventive pressure vessel comprises a continuous 720degree wrap d of the material comprising the bare vessel body 10,extending from a inner seam allowance bend 200 a in inner seam allowance200 to an outer seam allowance bend 170 a in outer seam allowance 170.Finally, FIG. 5 illustrates a potential space 360 separating outerportion 110 and inner portion 130, which may be used for containing orconveying fluid or some other physical substance.

The foregoing inventive method of manufacturing a multilayered pressurevessel allows for considerable flexibility in designing and customizingthe characteristics and features of the vessel and its various surfaces.For instance, while the fabric sheet is initially laid out flat,numerous attachments, auxiliary devices, surface textures and features,handles, grips, and so forth, can be affixed to the surface of a portionor portions of the fabric. Detail of this advantage is made more clearby the following descriptions of the second through fifth preferredembodiments of the inventive pressure vessel.

FIGS. 6–8 are end views in elevation of a second preferred embodiment ofthe pressure vessel of the present invention in various stages ofmanufacture. These views correspond to FIGS. 1–3 of the first preferredembodiment. As with the first preferred embodiment, a single sheet offlexible fabric 400 (viewed on edge) is provided and the geometry andgeneral relative dimensions of the outer portion 410 and inner portion420 are indicated by widths l 430 and l₁ 440, and by approximate midlineM. However, in this embodiment, attachment elements 450 and 460 areaffixed with attachment means 470, 480 preferably seams), to the outersurface 490 of outer portion 410, and the inner surface 500 of innerportion 420. Seam 520 is made at substantially the approximate midlineafter the inner and outer portions are folded, and manipulation of theassembly proceeds as described for the first preferred embodiment.Accordingly, upon completion of the vessel body 510 the seam includeshidden segments 520 a–d.

As will be readily appreciated, the attachment elements of thisembodiment generally comprise a flap of fabric or other flexiblematerial. When disposed on the exterior surface of the vessel body, thefabric flap may be employed for a variety of purposes, including theformation of a handle portion, construction of an exterior sleeve (as isdiscussed more fully in connection with FIGS. 10–14), formation of ahanging flap (FIG. 17). and connection means for joining the vessel bodyto other vessel bodies (FIGS. 19–20). However, depiction of theattachment as a loose fabric strip is for illustrative purposes only,the illustration intended to show the ease and convenience with whichexterior and interior surface attachments, sleeves, surface textures andthe like, can be applied to both the inner and outer portions of thefabric in the first stages of fabrication. This makes the formation ofmulti-passage vessels uniquely simple (see esp. FIG. 22).

FIG. 9 is a partial cross-sectional side view in elevation of selectedend fitting elements 600 adapted for installation on an end of thepressure vessel body 610 when the pressure vessel is intended for use asa structural member. FIG. 9A is a partial cross-sectional perspectiveview of the complete fitting of FIG. 9, also showing the terminalfitting elements. In this preferred embodiment of an end fitting,pressure vessel body 610 is wrapped around a retaining ring 620 which isthen snap fit over cap neck 630 having a threaded portion 640. Aretaining washer 650 is placed over retaining ring 620 and then an outerpressure lock ring 660 having a threaded portion 670 is screwed onto capneck 630. An inflatable bladder 680 may be retained by the end fitting.Its valve stem 690 is preferably disposed through a port plug 700 havinga stem aperture (not shown, see FIG. 12, ref. no. 970), and secured inplace with a washer 710 and nut 720. The port plug is oval-shaped tomatch an oval-shaped opening 730 in the terminal side 740 of cap neck630. The port plug 700 has an interior flange 750 which preventsejection of the port plug when the pressure vessel is under interiorpressure, but it allow for selective removal by simply turning the plugso that its smallest dimension will emerge from the opening 730. Capneck 630 may include a plurality of bolts or other fasteners extendingfrom the fitting, the orientation of which is dictated by the intendeduse and the contemplated configuration of adjoining structural members.

FIGS. 10–13 are various views of a third preferred embodiment of theinventive pressure vessel having a tubular configuration and adapted forthe installation of fittings at each of its ends. FIG. 10 is aperspective view showing the vessel body 800 having a plurality oftuning cable sleeves 810 a–d formed on the exterior surface 820 of theouter portion 830 of the vessel body. The tuning cable sleeves may bemade from fabric strips 840 a–d sewn or otherwise affixed at their edges850 a–d to the outer portion, wherein the fabric is not pulled taughtbut includes sufficient slack to produce the desired passage along thelength of the vessel body. Preferably, each tuning cable passageincludes a tuning cable 860 a–d extending from one end of the vesselbody to the other end.

FIG. 11 is a perspective view showing detail of the end of a tuningcable. This view shows that each tuning cable 860 generally includes acable having a threaded pin 870 welded at its end and a nut 880 screwedonto the threaded pin.

FIG. 12 is a perspective view of the pressure vessel of FIG. 10 showingan alternative end fitting 900 fully installed on the pressure vessel,while FIG. 13 is a side perspective view of a complete pressure vesselwith first and second end fittings 900 a, 900 b, respectively, at eachend of the pressure vessel and tuning cables installed between the endfittings. These views illustrate the operation of the tuning cables inproviding means to precisely adjust the length l₂ 910 of the vesselbody, which length may therefore be characterized as a tunable length.The end fitting includes a cap neck 920 and a pressure lock ring 930,which further includes a rim or collar 940 with throughholes (not shown)for insertion of the threaded pins 870 of the tuning cable ends. Nuts880 are then installed on the threaded pins so that tightening the nutsurges the fitting toward the fitting disposed on the opposite end of thevessel body, thereby slightly compressing the vessel body; loosening thenuts allows the vessel body to extend to a desired length. Once again,the fitting is preferably provided with an oval shaped opening 950selectively sealed with a port plug 960. The port plug includes a hole970 for insertion of a valve stem 980 of an inflatable bladder (notshown) disposed within the tubular vessel body.

Fitting 900 a may also include bolts 990 or other connection means forattaching the pressure vessel to other pressure vessels or to auxiliaryhardware. In this instance, the bolts are shown extending from thepressure lock ring, though it will be readily appreciated thatconnection means may be disposed on or about the fitting at a number ofsuitable locations, depending upon the configuration of the structure inwhich the pressure vessel is employed. It will also be readilyappreciated that ring fittings comprise the general configuration of endfittings for generally cylindrical embodiments of the pressure vessel.It is well known that such fittings can be equipped with numerous kindsof attachment mounts or connection means, including, among others,threaded studs, locking pins, bayonet mounts, clevis pins, flangededges, cord ends, webbing, belts, and the like. Accordingly, thepressure vessel may be adapted for use in slow to rapid assemblystructural units, from tents and inflatable bridges, to antennas,airfoils, and countless other structures. Finally, it will beappreciated that in those instances in which a generally tubular orcylindrical pressure vessel is provided with end fittings and aninflatable bladder, only one end fitting need be adapted for insertionof the bladder's valve stem or other gas inlet means.

FIG. 14 is an end view in elevation of a fourth preferred embodiment1000 of a pressure vessel body 1010 in which a plurality of tuning cablesleeves 1020 are disposed on the interior surface 1030 of the outerportion 1040 of the vessel body. Affixation of the fabric piecescomprising the cable sleeves and installation of the tuning cables 1050is accomplished in the manner described above.

FIG. 15 a cross-sectional end view in elevation of airfoil or wing 1100having tubular pressure vessels 1110 sized and configured in aside-by-side arrangement to form and function as a wing spar assembly.As spars the pressure vessels provide support and rigidity to preventbuckling or collapse of the upper and lower airfoil surfaces 1120, 1130,respectively, of the wing, as is well known in the art.

FIG. 16 is perspective view of a pressure vessel assembly 1200 showing aplurality of tubular pressure vessels 1210 in fluid communication withone another to form an integrated multi-chambered pressure tank. Eachpressure vessel includes at least one end fitting 1220 having a hose orother conduit 1230 placing the pressure vessel into fluid communicationwith an adjoining or nearby vessel or vessels. The assembly includes atleast one gas inlet 1240 for the introduction of a pressurized gas intothe assembly.

FIG. 17 is a perspective view of a fifth preferred embodiment 1300 of atubular pressure vessel 1310 having a flange 1320 attached with seams1330 to the outer surface 1340 of the vessel. The flange includesgrommets 1350 suitable for use in draping the pressure vessel from asupport line 1360 (FIG. 18).

FIGS. 19 and 20 are end views in elevation showing possibleconfigurations of connection means for adjoining tubular pressurevessels. The connection means 1400 (FIG. 19), 1500 (FIG. 20), comprisesa plurality of attachments sewn or otherwise affixed to the outersurfaces 1410, 1510 of the vessel bodies and to the surfaces of anyneighboring vessel body.

FIG. 21 is an end view showing a sixth preferred embodiment 1600 of theinventive multilayered pressure vessel. In this embodiment, two fabricsheets 1610, 1620 are initially laid out, one atop the other, each sheethaving outer and inner portions with differential widths suitable forforming first through fourth fluid passageways 1630, 1640, 1650, and1660, and having first through fourth layers 1670 a–d of materialforming the vessel body. As in the first preferred embodiment, the wrapforming the vessel is a continuous 720 degree wrap. When fullyconfigured, the vessel may include one to four passageways, dependingupon the dimensions of the partitioned layers and, therefore, how theyseparate and become spaced apart during construction. The seam 1680spans all layers but is hidden at the surface and includes hiddensegments, as earlier described.

FIG. 22 is an end view in elevation showing a seventh preferredembodiment 1700 of the inventive pressure vessel 1710 having multipleinterior fluid passages, in this instance first through third interiorfluid passages, 1720, 1730, 1740, each of which is defined by elongateflexible partition walls comprised of first through third materialattachments 1750, 1760, and 1770, affixed to the interior surface 1780of the vessel body. Location of the connections of the materialattachments to the interior surface of the vessel body is proximate afirst edge 1750 a, 1760 a, 1770 a. The attachments are then collectivelyjoined and affixed to one another proximate a second edge of eachattachment, 1750 b, 1760 b, 1770 b, respectively. While it is shown thatthe passageways are roughly equal in size and volume, it will be readilyappreciated that by varying the length of the partition walls, the size,shape, and volume of the passageways may be substantially altered. Inthis fashion, the pressure vessel of the present invention may beadapted for use as a multilayered, multipurpose fluid conveyingapparatus (i.e., a hose) for selectively conveying and dischargingdifferent fluids simultaneously (to be mixed at discharge), orseparately. For instance, the hose could be adapted for use as amulti-purpose fire hose, discharging a chemical fire retardant in oneinstance, and in another instance water.

FIG. 23 is a top plan view of a section of fabric 1800 sized andconfigured for construction into the eighth preferred embodiment of theinventive pressure vessel, comprising a cone-shaped pressure vessel body1900, as shown in FIG. 24. The principles and process of constructionare identical to those of the first embodiment. However, in contrast tothe substantially cylindrical embodiments of the present invention, inthis embodiment the initial section of fabric 1800 includes twoportions, each of which comprises a trapezium (a quadrilateral with onepair of opposite sides parallel) or a trapezoid (a quadrilaterals withno parallel sides), depending upon the ultimate size of the openingsdesired. In any event, the quadrilateral shapes are composed of a singlesection of fabric, which includes an inner portion 1810 and an outerportion 1820, substantially symmetrical with the inner portion about amidline axis 1830 which defines a shared side for each quadrilateralportion. The outer portion of the fabric (and the vessel) includesfirst, second, and third exposed sides 1840, 1850, 1860; the innerportion of the vessel includes corresponding first, second and thirdexposed sides, 1870, 1880, 1890. Sides 1870 and 1890 are shorter inwidth than sides 1840, and 1860, their counterparts in the outerportion. Thus, the inner and outer portions are not entirelysymmetrical, in that the inner portion must of necessity be slightlysmaller so as to form a passageway slightly smaller than that formed bythe outer portion.

When constructed, in a manner identical to that described above forother embodiments, the vessel body of the eighth preferred embodimentcomprises a truncated cone, having a large opening 1910 and a smallopening 1920 which has a smaller diameter than that of the largeopening. This shape is suitable for use in structures requiring supportmembers that taper in size, including, for example, an air foil or wing,as shown in FIG. 15. In most instances, the outer and inner portionswill be approximated over their opposing surfaces; however, it may bedesirable to provide a fluid passageway 1930 between the portions.

In an alternative to the eighth embodiment, the fabric section can bedivided to comprise quadrilaterals having substantially different sizesso that the constructed vessel has an inner passageway that issignificantly smaller than the outer passageway, and thus a well definedpassageway between the inner and outer portions.

Materials for making the inventive pressure vessel are selectedaccording to the intended application. In the most lightweight versions,the pressure vessel would be made of material having a filamentreinforced matrix structure, preferably a composite of high-tenacitycontinuous fibers and a flexible matrix material. Even more preferably,the fibers would be predominantly bias-oriented, the orientations beingoptimized to make the fibers bear the tensile loads in the structure.This would effectively minimize the need for stitching and fill (weft)fibers for strength. Currently available lightweight, high tensilestrength materials include, among others, such fabrics as aramid fiber,polyester fiber, gel-spun polyethylene fiber, aramid fiber based onmetaterephthalamide polymer, and nylon. Film-type materials can also beemployed, including such materials as polyethylene terephthalate filmand aluminized terephthalate film. However, it will be appreciated thatin numerous potential applications there will be no need for the use ofexotic materials, and even simple sheets of cotton, polyester,cotton/polyester blends, and so forth may be suitable. Non-fibrous andnon-porous natural and synthetic rubbers, polymers, and other elastomersmay also be employed. When fibrous materials are employed, coatings maybe applied to the material to increase strength and tailor the porosityand chemical reactivity of the vessel to its intended use. Selectivelyporous material, such as TYVEK® may also be employed, so that thepressure vessel may be employed as a filter. Alternatively, non-porousmaterial may be employed when the vessel is intended for use as avolumetric container. Other uses of the inventive apparatus, such as aconcrete form for columns, may entail fabrication from materials onlysufficiently non-porous to prevent impregnation by wet concrete.

The foregoing disclosure is sufficient to enable one having skill in theart to practice the invention without undue experimentation, andprovides the best mode of practicing the invention presentlycontemplated by the inventor. While there is provided herein a full andcomplete disclosure of the preferred embodiments of this invention, itis not intended to limit the invention to the exact construction,dimensional relationships, and operation shown and described. Variousmodifications, alternative constructions, changes and equivalents willreadily occur to those skilled in the art and may be employed, assuitable, without departing from the true spirit and scope of theinvention. Such changes might involve alternative materials, components,structural arrangements, sizes, shapes, forms, functions, operationalfeatures or the like.

Accordingly, the proper scope of the present invention should bedetermined only by the broadest interpretation of the appended claims soas to encompass all such modifications as well as all relationshipsequivalent to those illustrated in the drawings and described in thespecification.

1. A multilayered pressure vessel, comprising: at least one single plysheet of flexible material (100) having an approximate longitudinalmidline (M) dividing said sheet of flexible material into an innerportion (130) having an inner surface (190), an outer surface (180), anedge (195), a seam allowance (200), and a width (140), and an outerportion (110) having an inner surface (160), an outer surface (160), anedge (165), a seam allowance (170), and a width (120), wherein saidwidth of said outer portion is greater than said width of said innerportion; and a primary seam (250) binding said outer portion and saidinner portion to said sheet of flexible material at the approximatemidline and proximate said outer portion edge and said inner portionedge; wherein said sheet of flexible material is wrapped into asubstantially continuous, approximately 720 degree wrap to form a vesselbody in which said outer surface of said outer portion forms theexterior surface (150 a) of said multilayered pressure vessel, saidinner surface of said inner portion comprises the innermost interiorsurface (190 a) of said vessel body, said outer surface of said innerportion and said inner surface of said outer portion are in face-to-facerelation, and said seam is concealed by said seam allowance of saidouter portion.
 2. The multilayered pressure vessel of claim 1, whereinsaid outer portion and said inner portion are each substantiallyrectangular and said vessel body (10) is substantially cylindrical. 3.The multilayered pressure vessel of claim 1, wherein said outer portionand said inner portion are each a trapezium and said vessel body (1900)comprises a truncated cone shape.
 4. The multilayered pressure vessel ofclaim 1, wherein said apparatus has a proximate end (340) and a distalend (350), and wherein each end has an end fitting (600), at least oneof which includes gas inlet and outlet means (690).
 5. The multilayeredpressure vessel of claim 4, wherein at least one said fittings includes:a cap neck (630), said cap neck having a coupling means (640) and aterminal side (740); an outer pressure lock ring (660) coupled to saidcap neck through coupling means (670) complementary to said cap neckcoupling means; a retaining ring (620) snap fit over said cap neck andaround which is wrapped the pressure vessel body, said retaining ringinterposed between said cap neck and said outer pressure lock ring; anda retaining washer (650) is placed over said retaining ring andinterposed between said pressure lock ring, said retaining ring, andsaid cap neck.
 6. The multilayered pressure vessel of claim 5, furtherincluding a plurality of tuning cables (860) connected to and extendingbetween said end fittings.
 7. The multilayered pressure vessel of claim6, further including a plurality of cable tuning sleeves (840) disposedon said exterior surface of said apparatus, each cable tuning sleevecovering at least one tuning cable.
 8. The multilayered pressure vesselof claim 6, further including a plurality of cable tuning sleeves (1020)disposed between said outer portion inner surface and said inner portionouter surface, each of said sleeves containing at least one tuningcable.
 9. The multilayered pressure vessel of claim 4, further includinga hose for placing said apparatus into fluid communication with anothermultilayered pressure vessel.
 10. The multilayered pressure vessel ofclaim 1, further including at least connection means for connecting saidapparatus to other multilayered pressure vessels.
 11. A method of makinga pressure vessel, comprising the steps of: (a) providing a generallyelongate flexible material sheet (100) having a proximal end (340), adistal end (350), and first and second edges (165), (195); (b) foldingthe sheet by bringing the first edge downward and under the sheet toform an outer portion (110) having an outer portion flap (280), an outerpassageway (230), and a first seam allowance (170); (c) folding thesheet again by bringing the second edge upward and over the sheet toform an inner portion (130) having an inner portion flap (270), an innerpassageway (240), and a second seam allowance (200), and such that thefirst and second seam allowances overlap and such that a section (260)of sheet is interposed between the inner and outer portion flaps and thefirst and second seam allowances to form a multilayered configuration(20); (d) sewing a seam to make a single primary seam (250), which bindsthe layers of the multilayer configuration together; (e) providingpulling means (310) and affixing the pulling means to the inner portionupper flap (270) at the proximate end (340) of the sheet; and (f)pulling the inner portion into outer passageway (230) at the proximateend (340) while simultaneously turning outer portion (110) inside out bypulling its distal end (350) over the increasingly overlapping outer andinner passageways, thereby turning the apparatus inside out and pullingprimary seam (250) interiorly such that it is interposed between theouter portion (110) and the inner portion (130).
 12. The method of claim11, wherein at step (e) the pulling means is a line.
 13. The method ofclaim 11, wherein step (a) comprises providing a flexible material sheethaving an approximate longitudinal midline dividing the sheet intosubstantially rectangular inner and outer portions.
 14. The method ofclaim 11, wherein step (a) comprises providing a flexible material sheethaving an approximate longitudinal midline dividing the sheet into aninner portion comprising a trapezium and an outer portion comprising atrapezium.
 15. A multilayered pressure vessel produced according to theprocess of claim
 11. 16. A multilayered pressure vessel producedaccording to the process of claim
 13. 17. A multilayered pressure vesselproduced according to the process of claim 14.